Methods of fabricating nitride-based transistors with a cap layer and a recessed gate
AssigneeCree, Inc.
InventorsScott Sheppard, Richard Peter Smith
Life of this patent
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Abstract
An anneal of a gate recess prior to formation of a gate contact, such as a Schottky contact, may reduce gate leakage and/or provide a high quality gate contact in a semiconductor device, such as a transistor. The use of an encapsulation layer during the anneal may further reduce damage to the semiconductor in the gate recess of the transistor. The anneal may be provided, for example, by an anneal of ohmic contacts of the device. Thus, high quality gate and ohmic contacts may be provided with reduced degradation of the gate region that may result from providing a recessed gate structure as a result of etch damage in forming the recess.
Claims16
A method of fabricating a high electron mobility transistor (HEMT), comprising:
- forming a channel layer;
- forming a barrier layer on the channel layer;
- forming a cap layer on the barrier layer;
- forming spaced apart ohmic contact recesses in the cap layer;
- forming ohmic contact material patterns in the ohmic contact recesses;
- forming a gate recess in the cap layer that extends to the barrier layer;
- annealing the barrier layer, channel layer, ohmic contact material patterns and cap layer with the gate recess, the ohmic contact material being annealed for a first time;
- and then
- forming a gate contact in the annealed gate recess, wherein the step of annealing is preceded by forming an encapsulation layer on the cap layer, the ohmic contact material patterns and the gate recess and wherein the step of forming the gate contact is preceded by removing the encapsulation layer.
A method of fabricating a high electron mobility transistor, comprising:
- forming a first layer of GaN based semiconductor material on a substrate;
- forming a second layer of GaN based semiconductor material on the first layer, the second layer being configured to induce a two-dimensional electron gas in a region proximate an interface between the first layer and the second layer;
- forming a third layer of GaN based semiconductor material on the second layer of GaN based semiconductor material;
- forming spaced apart ohmic contact recesses in the third layer of GaN based semiconductor material;
- forming ohmic contact material patterns in the ohmic contact recesses;
- forming a gate recess in the third layer that extends to the second layer;
- annealing the first layer, second layer, ohmic contact material patterns and third layer with the gate recess, the ohmic contact material being annealed for a first time;
- and then
- forming a gate contact in the annealed gate recess.
Dependencies are inferred from the claim text.